Arkansas State Plant Board votes to ban dicamba use after April 15

Arkansas State Plant Board members voted Wednesday (Nov. 8) during a public hearing and board meeting to ban dicamba in Arkansas during a bulk of the 2018 growing season.

Dicamba is used to kill weeds, especially the pigweed, in row crops. It’s primarily used in soybean and cotton production. Arkansas farmers planted 3.7 million soybean acres this year, making it the 11th largest soybean producing state.

Changes will prohibit the use of the herbicide in Arkansas between April 16 and Oct. 31. The regulations include exemptions for the use of dicamba in pastures, rangeland, turf, ornamental, direct injection for forestry, and home use. This regulation change is now subject to final approval by the executive subcommittee of the Arkansas Legislative Council.

The Board’s regulatory changes concerning the use of dicamba were subject to a 30-day public comment period which ended Oct. 30. More than 29,000 written comments were received by email, mail, and fax. Thirty-seven people testified at the public hearing.

Dr. Mark Cochran, vice president-agriculture for the University of Arkansas System, said the decision was based on the best evidence available.

“The plant board and the dicamba task force that preceded it made a decision based on the best evidence from land grant research conducted not only by the scientists of the University of Arkansas System Division of Agriculture, but also by their peers in Missouri, Tennessee, Indiana, and other states, and from additional information made available from all other sources. We are proud of the work that our weed scientists and agronomists have done in service to the people of Arkansas and beyond,” Cochran noted in a statement. “Our weed scientists and agronomists will continue to work diligently toward tools and techniques to help Arkansas farmers economically manage the challenge of resistant weeds.”

ASPB will host a public hearing and board meeting to consider changes to the Arkansas Pesticide Control Act Regulation, regulations under Act 410. ACA 2-16-402 (b), on Dec. 12. The proposed regulations would clarify ASPB’s ability to request additional information about a pesticide before it is registered for use in Arkansas.

The state instituted a 120-day ban on July 11 after a slew of damage complaints. Scientists, farmers, and others with an interest in the use of the herbicide were appointed to a task force by Gov. Asa Hutchinson and others.

In May, ASPB began receiving numerous complaints about crop damage from suspected dicamba drift. It received 963 damage complaints from 26 counties, mostly in Northeast Arkansas where the herbicide is used at a higher rate. It is the most complaints the ASPB has ever received in one year.

Dicamba has been banned in several states. Dicamba has been used as an herbicide for more than 50 years to manage 200 broad leaf weeds. It is a Weed Science Society of America Group 4 synthetic auxin – a plant hormone that causes plants to exhibit uncontrolled growth, according to the University of Arkansas. It is more volatile in warmer climates.

ASPB decided earlier this year to allow one formulation, Engenia dicamba, to be used in the state to fight pigweed, an aggressive weed that has plagued farmers in recent years. About 35% of the state’s 3.5 million soybean acres were planted with genetically-altered dicamba tolerant seeds. About 75% (300,000 acres) of the state’s cotton crop was planted with dicamba resistant seeds.

Scientists theorized dicamba was drifting into adjacent crop fields, gardens, and other places. Misapplications, weather conditions, or some other unknown factors may have caused the alleged drift. Tests proved the new formulations were less volatile than older ones, but there was still volatility, and it could last up to 36 hours after it was sprayed. Dicamba can attach to dust particles, meaning it can travel much further from target sites than previously thought.

Some additives enhanced the volatility. Ammonium sulfate and glufosinate increase the damage capabilities of dicamba. Researchers found damage could spread up to 220 feet away from an application site, nearly double the buffer distance the Environmental Protection Agency requires between dicamba and non-dicamba fields. Tests showed that if the wind blew in one direction for several hours, drift could cause damage on adjacent fields and then if the wind changed hours later, the same amount of damage would be caused there.